Quenching of formed glass sheets to provide annealing, heat strengthening and tempering has not previously provided uniform distribution of the quenching so as to provide a uniformly cooled glass sheet with consequent uniformity of the glass mechanical stresses resulting from such cooling. This is because formed glass sheets have oppositely facing curved surfaces over which conventional quench units do not provide uniform distribution of quench gas, unlike flat glass sheets over whose oppositely facing flat surfaces the quench gas has been more evenly distributed.